The Project Management Plan may be a single detailed document or it can be composed of one or more subsidiary planning documents. These additional planning documents provide guidance and direction for specific management, planning, and control activities such as schedule, cost, risk, staffing, change control, communications, quality, procurement, deployment, etc. Each of the subsidiary planning documents should be detailed to the extent required by the specific project.  If subsidiary documents are developed, they should be referenced in the main Project Management Plan.  The size and time invested to develop a Project Management Plan should be balanced with the complexity of the project.